One aspect is that being excellent at one thing is hard. Be really good at two things. And thats how you will stand out because it is the fusion of two skils that makes you unique.
And then there is a quote by Robert Anson Heinlein, if you want to take it to heart and live on other extreme. By no means it is a career advice but surely an interesting take.
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.”